From pending to ready
Just after a purchase, the cashback sits as pending while the shop confirms that the sale went through. Once it is approved, the amount becomes ready for payout.
Request a payout
When you have earned enough, you ask for a payout to your bank account. You control it yourself from My account, and the money is yours to take out when you want.
Why it takes a little time
The wait is there because the shop has to confirm the purchase before the money can be released. It is a safeguard against cashback being paid out on orders that are later returned.